1. Field of the Invention
This invention relates to 5-keto-L-ascorbic acid-5,5-dimethyl ketal and to a process for its preparation by the reaction of methyl 2,5-diketogluconate-5,5-dimethyl ketal with an inorganic base in an alcohol or aqueous solvent system followed by neutralization of the 5-keto-L-ascorbic acid-5,5-dimethyl ketal inorganic salt thus produced. The 5,5-dimethyl ketal of 5-keto-L-ascorbic acid is an effective antioxidant, an antiscorbutic agent, and an intermediate for production of 5-keto-L-ascorbic acid, also an antiscorbutic agent, and L-ascorbic acid.
2. Description of the Prior Art
Finkle et al., Biochim. Biophys. Acta, 38, 332-339 (1960), proposed 5-keto-L-ascorbic acid as an intermediate in the biosynthesis of ascorbic acid in plants. However, no enabling disclosure as to its preparation is given, and no evidence has been found to date to support this proposal.